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  <title>检查对象或类是否具有该属性</title>

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</div><hr /><div id="function.property-exists" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">property_exists</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.1.0)</p><p class="refpurpose"><span class="refname">property_exists</span> &mdash; <span class="dc-title">检查对象或类是否具有该属性</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.property-exists-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="type">bool</span> <span class="methodname"><strong>property_exists</strong></span>
    ( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$class</code></span>
   , <span class="methodparam"><span class="type">string</span> <code class="parameter">$property</code></span>
   )</div>

  <p class="para rdfs-comment">
   本函数检查给出的 <em><code class="parameter">property</code></em> 是否存在于指定的类中（以及是否能在当前范围内访问）。
  </p>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    As opposed with <span class="function"><a href="function.isset.html" class="function">isset()</a></span>,
    <span class="function"><strong>property_exists()</strong></span> returns <strong><code>TRUE</code></strong> even if the property
    has the value <strong><code>NULL</code></strong>.
   </p>
  </p></blockquote>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.property-exists-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">class</code></em></dt>

      <dd>

       <p class="para">
        字符串形式的类名或要检查的类的一个对象
       </p>
      </dd>

     
    
     <dt>
<em><code class="parameter">property</code></em></dt>

      <dd>

       <p class="para">
        属性的名字
       </p>
      </dd>

     
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.property-exists-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   如果该属性存在则返回 <strong><code>TRUE</code></strong>，如果不存在则返回 <strong><code>FALSE</code></strong>，出错返回 <strong><code>NULL</code></strong>。
  </p>
 </div>


 <div class="refsect1 notes" id="refsect1-function.property-exists-notes">
  <h3 class="title">注释</h3>
  <blockquote class="note"><p><strong class="note">Note</strong>: <p class="para">如果此类不是已知类，使用此函数会使用任何已注册的
<a href="language.oop5.autoload.html" class="link">autoloader</a>。</p></p></blockquote>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    The <span class="function"><strong>property_exists()</strong></span> function cannot detect properties
    that are magically accessible using the <a href="language.oop5.overloading.html#language.oop5.overloading.members" class="link"><em>__get</em></a>
    magic method.
   </p>
  </p></blockquote>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.property-exists-changelog">
  <h3 class="title">更新日志</h3>
  <p class="para">
   <table class="doctable informaltable">
    
     <thead>
      <tr>
       <th>版本</th>
       <th>说明</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td>5.3.0</td>
       <td>
        This function checks the existence of a property independent of 
        accessibility.
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>
 </div>

 <div class="refsect1 examples" id="refsect1-function.property-exists-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-4967">
    <p><strong>Example #1 A <span class="function"><strong>property_exists()</strong></span> example</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">class&nbsp;</span><span style="color: #0000BB">myClass&nbsp;</span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;</span><span style="color: #0000BB">$mine</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;private&nbsp;</span><span style="color: #0000BB">$xpto</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;static&nbsp;protected&nbsp;</span><span style="color: #0000BB">$test</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;static&nbsp;function&nbsp;</span><span style="color: #0000BB">test</span><span style="color: #007700">()&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">property_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'myClass'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'xpto'</span><span style="color: #007700">));&nbsp;</span><span style="color: #FF8000">//true<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">}<br />}<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">property_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'myClass'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'mine'</span><span style="color: #007700">));&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//true<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">property_exists</span><span style="color: #007700">(new&nbsp;</span><span style="color: #0000BB">myClass</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'mine'</span><span style="color: #007700">));&nbsp;</span><span style="color: #FF8000">//true<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">property_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'myClass'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'xpto'</span><span style="color: #007700">));&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//true,&nbsp;as&nbsp;of&nbsp;PHP&nbsp;5.3.0<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">property_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'myClass'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'bar'</span><span style="color: #007700">));&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//false<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">property_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'myClass'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'test'</span><span style="color: #007700">));&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//true,&nbsp;as&nbsp;of&nbsp;PHP&nbsp;5.3.0<br /></span><span style="color: #0000BB">myClass</span><span style="color: #007700">::</span><span style="color: #0000BB">test</span><span style="color: #007700">();<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.property-exists-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.method-exists.html" class="function" rel="rdfs-seeAlso">method_exists()</a> - 检查类的方法是否存在</span></li>
   </ul>
  </p>
 </div>

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